The present invention relates to a motor-driven compressor, and more specifically, a scroll type motor-driven compressor that drives a movable scroll by using an electric motor.
For example, Japanese Laid-Open Patent Publication No. 11-351175 discloses a scroll type motor-driven compressor that includes a movable scroll driven by an electric motor. The movable scroll receives drive force from the electric motor via a rotary shaft rotated by the electric motor. Lubrication of a main bearing, which rotationally support the rotary shaft, is important. The main bearing of the motor-driven compressor disclosed in the above publication is lubricated by supplying oil stored in a bottom portion of a motor chamber in a middle housing to the main bearing via an oil supply hole. In the motor-driven compressor, to supply oil stored in the bottom portion of the motor chamber via the oil supply hole, the motor chamber is exposed to discharge pressure, which is higher than suction pressure.
However, in a state in which the motor chamber is exposed to discharge pressure, the temperature of the motor chamber is relatively high. The temperature of the electric motor is increased, accordingly, which is not favorable for the motor performance.